The organization, founded in 1970, went into hibernation through the 1980s and was reborn in 1990. Now -- with a paid membership of 5,800 and its top executive sitting on the board overseeing San Francisco's public transit, parking and traffic operations -- the bike coalition is moving aggressively to enact its goal of making the streets of San Francisco a bicycling mecca "where cars are rare and travel slowly."

In the past decade, the city -- responding to the demands of the Bicycle Coalition -- has added bike lanes, required commercial developers to provide bike parking and equipped Muni buses with bike racks.

But as the crusade moves forward and cycling in San Francisco gains in popularity, a pushback can be felt.

The coalition's lobbying for a proposal to make a portion of Golden Gate Park car-free on Saturdays won a narrow victory at the Board of Supervisors this spring, but Mayor Gavin Newsom applied the brakes with a veto.

And in June, a San Francisco Superior Court judge put the city's bike plan on hold. The plan, which won unanimous backing by the supervisors and the mayor last year, maps out an ambitious five-year strategy to make it easier and safer for cyclists to get around town.

Critics sued, charging that the city did not conduct a review that adequately analyzed the plan's effects; for example, the city may have to remove street parking and traffic lanes to make room for cyclists.

The judge's ruling effectively prevents city officials from moving forward with much of the plan until the court rules on the merits of the litigation. The hearing has been set for Sept. 13.

Despite the setbacks, bicycle advocates in San Francisco aren't deterred.

"There is broad public support for better biking conditions," said Leah Shahum, who runs the San Francisco Bicycle Coalition. She said a new poll of 400 likely voters by David Binder Research found that nearly 3 in 4 respondents favored creating more bike lanes in San Francisco.

The fact that the monthly Critical Mass ride -- an event organized independently of the Bicycle Coalition at which anywhere from dozens to thousands of bikers take to the streets on the last Friday of the month -- hasn't erupted into chaos for nearly a decade probably has helped move public opinion in that direction.

"The bike coalition is at the cutting edge of urban environmentalism. It reduces our reliance on foreign oil, cuts down pollution, helps ease traffic congestion and makes the city more livable," said Supervisor Jake McGoldrick, who represents the Richmond District in a famously liberal city where politicians work hard to put green-friendly credentials on their resumes.

In addition to lobbying for more bike lanes, the Bicycle Coalition is urging city officials to better maintain streets now pocked with potholes, to do more to prevent bicycle thefts and to enact measures to slow the speed of cars.

Jim Town, a 26-year-old math teacher, uses his 15-speed bicycle -- and Caltrain -- to commute from his home in San Francisco's Western Addition to his job in Palo Alto. He thinks San Francisco is a good place to ride, especially when bike lanes are available.

"I feel like I don't have to assert myself as much when there's a lane; drivers are more respectful," said Town, who only had one bad experience with a driver who was in a hurry to make a right-hand turn when they were both stopped at a red light. "I find that bicycling is a good way to get around; it's often faster than driving when there's a lot of traffic."

The 2000 U.S. Census found that about 2 percent of the commuters in San Francisco pedal to work or school. City Hall set a goal to push that to 10 percent by 2010.

Advocates say that can't be done without the completion of a citywide bicycle network that likely would mean less room on the city's streets to drive and park cars -- a prospect that adds fuel to the tension in the city between motorists and bicyclists.

Rob Anderson is fed up. An active blogger (www.district5diary.blogspot.com), he sued the city to stop implementation of the bike plan. Anderson started a group -- he won't say how many members it has, but by all accounts there aren't many -- called "Ninety-Nine Percent." The name is intended to highlight the fact that only a sliver of residents rely on bicycles and that the vast majority still drive, use public transit and walk.

The San Francisco Bicycle Coalition "has completely free rein at City Hall. No one challenges them," he said.

Chris Albanese agrees. He owns Antiquario, a store on the 1600 block of Market Street. In May, the city removed parking from the front of his shop to put in a new bike lane. He said that merchants in the area, who feared a drop in business, were given little notice to protest, and that those who did could not get a fair hearing. The city's creation of new parking spaces around the corner, he said, hasn't helped.

"The removal of the meters has all but eliminated new business and has greatly inconvenienced my established customers," Albanese said. "But the real story here is not my loss of business. It's about the bike coalition's overwhelming and undue influence on public officials and public policy."

There are few who would dispute that the Bicycle Coalition wields influence. In addition to being one of the biggest, if not the biggest, advocacy groups in the city, it has leaders who are politically savvy and media-friendly.

They work within the system -- Shahum's appointment to the Municipal Transportation Agency board of directors is just one example -- and have been working to build alliances with other well-organized advocacy groups, such as Rescue Muni, Walk San Francisco and the Sierra Club.

Bike coalition members don't hesitate to contact elected officials at City Hall, and the organization makes it easy by supplying preprinted postcards with the message of the moment.

During the bike coalition's first "Bike to Work Day" in the 1990s, Supervisor Tom Ammiano was the only elected official to participate in the event. Now, most of the local pols do. Even Newsom, who hesitates to put on hats for fear of messing his gelled hair, dons a helmet for the photo-op ride to City Hall during the morning commute.

Bike coalition leaders also have shown that they're willing to compromise and are in it for the long haul. Take, for example, the proposal in the mid-1990s to ban cars on Market Street. The business community revolted, and bike advocates backed down. Now, however, "we are pushing to have fewer cars on Market Street," Shahum said. One of the ideas is to force cars to turn off Market Street at several downtown intersections to discourage drivers from using the busy corridor.

Another example is the proposal to limit auto traffic in Golden Gate Park on Saturdays, something that had been done on Sundays and holidays.

After Newsom killed the legislation, backers of the "Healthy Saturdays" plan contemplated putting the issue on the November ballot, but backed off at the last minute when Newsom said he would work on coming up with a negotiated compromise. And if that doesn't happen, Shahum said, there is always next year's fall ballot -- which just happens to be when the next mayor's race will be decided.

The Bicycle Coalition endorses candidates, and getting the group's nod of approval is coveted.

"These politicians want to look green, and there are only so many things they can do at the local level," Shahum said.

McGoldrick, the supervisor representing the Richmond District, said supporting the bike coalition's agenda isn't an issue of quid pro quo. Instead, he maintained, the group's agenda resonates with the progressive majority of the Board of Supervisors and a large segment of the public.

"I don't think it's so much politics as policy," he said.

S.F. Bicycle Coalition facts
-- Founded: 1970
-- Went into hibernation: 1980s
-- Re-emerged: 1990
-- Annual budget: $485,000
-- Number of paid staff: 5
-- Number of dues-paying members: 5,800
Sources: San Francisco Municipal Transportation Agency,
San Francisco Bicycle Coalition
Few ride to work
Percentage of people biking to their jobs:
San Francisco: 1.9
California: 0.8
United States: 0.4
Source: U.S. census
The Streets of San Francisco
Paved street area of San Francisco: 195,000,000 square feet
Total highway and street miles: 1,088
-- Lanes reserved for bicycles: 40 miles
-- Protected pathways separated from motor vehicles: 23 miles
-- Signed bike routes shared with vehicles: 82 miles
-- Wide Curb lanes in which bikes and cars can
travel side by side: 56 miles
Total bicycle route miles: 201 miles
Source: San Francisco Municipal Transportation Agency